diff --git a/include/haproxy/pool.h b/include/haproxy/pool.h
index 2f5d7b1d3..a13d0eb7c 100644
--- a/include/haproxy/pool.h
+++ b/include/haproxy/pool.h
@@ -108,6 +108,7 @@ void *pool_alloc_nocache(struct pool_head *pool);
 void pool_free_nocache(struct pool_head *pool, void *ptr);
 void dump_pools_to_trash(void);
 void dump_pools(void);
+int pool_parse_debugging(const char *str, char **err);
 int pool_total_failures(void);
 unsigned long pool_total_allocated(void);
 unsigned long pool_total_used(void);
diff --git a/src/haproxy.c b/src/haproxy.c
index b62f30534..030a97325 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1649,11 +1649,19 @@ static void init_args(int argc, char **argv)
 			else if (*flag == 'd' && flag[1] == 'W')
 				arg_mode |= MODE_ZERO_WARNING;
 			else if (*flag == 'd' && flag[1] == 'M') {
-				mem_poison_byte = flag[2] ? strtol(flag + 2, NULL, 0) : 'P';
-				if (mem_poison_byte >= 0)
-					pool_debugging |=  POOL_DBG_POISON;
-				else
-					pool_debugging &= ~POOL_DBG_POISON;
+				int ret = pool_parse_debugging(flag + 2, &err_msg);
+
+				if (ret <= -1) {
+					if (ret < -1)
+						ha_alert("-dM: %s\n", err_msg);
+					else
+						printf("%s\n", err_msg);
+					ha_free(&err_msg);
+					exit(ret < -1 ? EXIT_FAILURE : 0);
+				} else if (ret == 0) {
+					ha_warning("-dM: %s\n", err_msg);
+					ha_free(&err_msg);
+				}
 			}
 			else if (*flag == 'd' && flag[1] == 'r')
 				global.tune.options |= GTUNE_RESOLVE_DONTFAIL;
diff --git a/src/pool.c b/src/pool.c
index 2cb37f345..4998f09b5 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -891,6 +891,34 @@ unsigned long pool_total_used()
 	return used;
 }
 
+/* This function parses a string made of a set of debugging features as
+ * specified after -dM on the command line, and will set pool_debugging
+ * accordingly. On success it returns a strictly positive value. It may zero
+ * with the first warning in <err>, -1 with a help message in <err>, or -2 with
+ * the first error in <err> return the first error in <err>. <err> is undefined
+ * on success, and will be non-null and locally allocated on help/error/warning.
+ * The caller must free it. Warnings are used to report features that were not
+ * enabled at build time, and errors are used to report unknown features.
+ */
+int pool_parse_debugging(const char *str, char **err)
+{
+	char *end;
+	int v;
+
+
+	/* if it's empty or starts with a number, it's the mem poisonning byte */
+	v = strtol(str, &end, 0);
+	if (!*end || *end == ',') {
+		mem_poison_byte = *str ? v : 'P';
+		if (mem_poison_byte >= 0)
+			pool_debugging |=  POOL_DBG_POISON;
+		else
+			pool_debugging &= ~POOL_DBG_POISON;
+		str = end;
+	}
+	return 1;
+}
+
 /* This function dumps memory usage information onto the stream interface's
  * read buffer. It returns 0 as long as it does not complete, non-zero upon
  * completion. No state is used.